WSPR (pronounced "whisper") stands for "Weak Signal Propagation Reporter". It is a computer program used for weak-signal radio communication between amateur radio operators. The program was initially written by Joe Taylor, K1JT, but is now open source and is developed by a small team. The program is designed for sending and receiving low-power transmissions to test propagation paths on the MF and HF bands. WSPR implements a protocol designed for probing potential propagation paths with low-power transmissions. Transmissions carry a station's callsign, Maidenhead grid locator, and transmitter power in dBm. The program can decode signals with S/N as low as -28 dB in a 2500 Hz bandwidth. Stations with internet access can automatically upload their reception reports to a central database called WSPRnet, which includes a mapping facility.
Beneath you will find my Home Made U3 WSPR Transmitter with an output of 200 mW & 500 mW (switchable)... The Ultimate3 QRSS Transmitter Kit is the third version in the "Ultimate" QRSS/WSPR kit trilogy. It can produce QRSS, Hell and WSPR slow-signal modes anywhere from audio to 10m and above. Plug-in LPF filters are available for all 12 HF/LF bands.
